The initial five year funding period of this Program Project Grant was remarkably successful in the generation and characterization of several new, promising genetically engineered viruses that are candidates for evaluation in clinical trials of patients with malignant glioma. These newly constructed viruses were extensively studied and characterized in both in vitro and in vivo models to demonstrate proof-of-principle, safety and efficacy in order to select the optimal virus(es) for administration to humans. This project will capitalize on our clinical trial experience in Phase I to III studies of retrovirus, adenovirus and engineered herpes simplex virus (HSV) in the treatment of gliomas. Importantly, we developed extensive experience in the first use of a genetically engineered HSV for the treatment of human glioma in a Phase I clinical trial, which continues in a Phase Ib study. We propose the following: Aim 1 will identify appropriate genetically engineered HSV for clinical evaluation by comparing our most promising viruses to G207, which we have previously examined in clinical trials, and to proceed with production of appropriate viruses for clinical grade material. Aim 2 will complete final evaluations with clinical grade viruses (Good Manufacturing Practice [GMP]-produced virus(es)) and to prepare an investigator-initiated IND(s) for evaluation by the NIH DNA Recombinant Advisory Committee and the Food and Drug Administration. With regulatory approvals, Aim 3 will be to design, organize, conduct and analyze Phase I trial(s) that evaluate a clinical HSV candidate alone or, ultimately, with radiation therapy.